A variable displacement engine may include valve operators to selectively deactivate one or more engine cylinders. Further, the one or more cylinders that may be deactivated, may be deactivated according to predetermined cylinder patterns that reduce engine noise and vibration but have capacity to provide a predetermined amount of torque. A cylinder pattern may describe which cylinders of an engine operate and combust air and fuel. For example, a four cylinder engine having a firing order of 1-3-4-2 may operate with a pattern of cylinders 1, 3, and 4. The cylinder patterns may be varied over time or operating conditions to improve engine operation and control engine emissions. However, some cylinder patterns may not be available at selected engine speeds because engine vibration and/or noise may be greater than desired. Consequently, the engine may not operate as efficiently as if a greater number of cylinder operating patterns were available.
The inventor herein has recognized the above-mentioned disadvantages and has developed a method for operating vehicle driveline, comprising: estimating a plurality of engine fuel consumption values for operating an engine coupled to a transmission in three different gears while the transmission is engaged in a gear; and engaging one of the three different gears in response to the plurality of engine fuel consumption values.
By estimating a plurality of fuel consumption values based on different activated cylinders and/or cylinder patterns for operating an engine coupled to a transmission in three different gears, it may be possible to provide the technical result of improving engine fuel economy while lowering engine noise and vibration. For example, engine fuel consumption may be estimated for a plurality of active engine cylinders and cylinder patterns at a present engine speed, a lower engine speed expected after a transmission upshift, and a higher engine speed expected after a transmission downshift. An actual total number of active cylinders and transmission gear that reduce engine fuel consumption may be selected and activated by changing the actual total number of active cylinders and the transmission gear to the values that reduce engine fuel consumption.
The present description may provide several advantages. In particular, the approach may reduce engine fuel consumption. In addition, the approach may increase an actual total number of available cylinder patterns with which to operate the engine. Further, the approach may improve engine durability.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.